1. Field of the Invention
The present invention relates to tanks for holding a liquid, and, more particularly, to a liquid-containing tank that is carried by a truck and a method of manufacturing the same.
2. Description of the Related Art
Tanks for carrying a liquid on the back of a truck are well known. Such tanks carry a wide variety of liquids, such as gasoline, chemicals and water. A problem is that the liquid within the tank acquires momentum as it is transported by the truck, and when the truck accelerates or decelerates, the inertia of the liquid causes it to slosh against the front end or the rear end of the tank. The forces associated with this sloshing, as well as the resulting change in the center of gravity of the truck, may cause the truck to become destabilized. Such destabilization may cause the driver to lose control of the truck, or may even cause the truck to overturn. This problem is especially acute in the case of fire trucks, which are required to carry a tank of water to a fire as quickly as possible. In order to lower the center of gravity, and thereby increase the stability of the truck, it is known to form the tank with an elliptical cross section, with the longer cross width of the ellipse extending in the horizontal direction.
Another problem is that the force exerted by the sloshing of the liquid within the tank can adversely affect the structural integrity of the tank. In order to withstand these forces, it is known to form the tanks of a heavy metal material and/or with especially thick outside walls. This increases both the cost and weight of the tank.
It is known to place concave baffles in a tank which extend across the entire width of the tank. The intent of the concave baffles is to break the total water volume into smaller volumes that individually create less surge force when the tank is accelerated or decelerated. A problem is that since all of the water within a compartment collides with a same baffle and rebounds in an opposite direction, the resultant force of such collision is still very high, and may lead to instability of the truck. Also, after the water rebounds off of the baffle, it then collides again with another baffle or a tank wall, thereby causing more instability. Further, because of the concave shape, the baffles are difficult to manufacture and install.
It is known to manufacture such liquid-containing tanks by separately forming a bottom half and a top half of the tank. The two halves are then bolted and welded together. The problem is that the process of bolting and welding is labor intensive and therefore expensive. Also, leaks may form between the two halves of the tank.
What is needed in the art is a liquid-containing tank which can reduce the forces associated with the liquid sloshing against the inner walls of the tanks, while at the same time having greater structural integrity. What is also needed is a method of producing such a tank which is efficient and results in a lessened probability of leakage.
The present invention provides a water tank having staggered internal baffles which cause the water within the tank to swirl between the baffles when the tank is accelerated or decelerated. The baffles also serve to increase the structural strength of the tank. Further provided is an efficient method of producing such a tank.
The invention comprises, in one form thereof, a tank containing a liquid while being transported by a moving vehicle. The tank includes a shell having an annular wall interconnecting opposite longitudinal end walls. The annular wall and the end walls define an interior compartment. The shell also has a substantially horizontal length direction and a substantially horizontal width direction perpendicular to the length direction. Two substantially planar longitudinal baffles are disposed within the interior compartment of the shell. Each longitudinal baffle is oriented substantially vertically and substantially parallel to the length direction of the shell. Each longitudinal baffle has a first side facing the annular wall. Each longitudinal baffle also has a second side. The second sides face each other. A plurality of substantially planar latitudinal baffles are disposed within the interior compartment of the shell. Each latitudinal baffle is oriented substantially vertically and substantially parallel to the width direction of the shell. First ones of the latitudinal baffles are each disposed between a first side of a corresponding longitudinal baffle and the annular wall. Second ones of the latitudinal baffles are disposed between the second sides of the two longitudinal baffles. The second latitudinal baffles are substantially staggered relative to the first latitudinal baffles along the length direction of the shell.
An advantage of the present invention is that, when the tank is accelerated or decelerated, the baffles guide the water within the tank to swirl from side to side and in vertical directions as the water""s inertia causes it to flow along the length of the tank. This side to side and vertical dispersion of the water greatly reduces the surge forces exerted on the walls of the tank, and on the truck that carries the tank.
Another advantage is that the baffles increase the structural strength of the tank, thereby allowing the walls of the tank to be formed of a thinner and lighter material.
Yet another advantage is that the tank can be manufactured with a minimum amount of labor, and in such a way that the possibility of leakage is greatly reduced.